1. Field of the Invention
The present invention relates generally to drilling oil or gas wells and more particularly to methods and compositions for sealing fractures, voids, and pores of subterranean formations.
2. Description of the Background
During drilling or completion, a bore hole may leak bore hole fluids at a certain pressure level into openings such as a fracture, void or pore connected to the bore hole. These openings are formed either by naturally existing faults, fissures, fractures, voids or vugs penetrated by the wellbore or by fractures artificially induced by abnormally wellbore pressure. Drilling fluids are generally very expensive and it is desirable that the fluids not be lost within “lost circulation zones.” Moreover, circulation of fluids through the borehole is important for most drilling operations for many reasons, as is well known to those of skill in the art. Therefore, sealing the fracture, void or pore is necessary for rig operations to proceed.
In the past, fibrous, pelleted and particulate lost circulation materials have been used to form the needed seal in the borehole. For instance, fibers, almond shell, graphite, peanut hull, cotton burrs, oat hulls, and ground marble are all used for sealing fractures, voids and pores. However, these materials may not always form a reliable seal due to a wide range of different downhole conditions.
Consequently, there remains a long felt need for improved methods and compositions to prevent or reduce lost circulation problems. Because those skilled in the art have recognized and attempted to solve these problems in the past without reliable success, they will appreciate the present invention, which addresses these and other problems.